In order to maintain access to a $4 billion line of credit, Chesapeake Energy Corp. (IW 1000/200) pledged almost all of its natural gas fields, real estate and derivatives contracts as the shale gas producer grapples with falling energy prices. The stock was the top performer in the Standard & Poor’s 500 Index.

Chesapeake amended a secured revolving credit agreement that matures in 2019 with lenders, who agreed to postpone the next evaluation until June 2017, the Oklahoma City-based company said on April 11. Such reassessments normally occur twice a year. In exchange, Chesapeake pledged “substantially all of the company’s assets, including mortgages encumbering 90% of all the company’s proved oil and gas properties” as collateral, according to a regulatory filing on April 11.

Chesapeake’s stock and bonds have fallen amid investor concern over the second-largest U.S. gas driller’s ability to shoulder a debt load three times larger than its market value. The company has slashed its debt load by more than half a billion dollars since the end of September, and surprised analysts and investors by raising twice as much cash as expected from fourth-quarter divestitures of a portfolio of small gas holdings across several states.

At the same time, CEO Doug Lawler has taken advantage of the slide in the company’s own bond prices to snatch up the debt at steep discounts, conserving future cash flows that would be eaten up by interest payments. Last month, Chesapeake exchanged 17.26 million new shares for about $73 million in senior notes and has said it is targeting another $500 million to $1 billion in assets sales

The lenders’ agreement will provide Chesapeake “time to ride out a low commodity price environment,” Citigroup Inc. analysts led by Marisa Moss said in a note to clients on Monday. The company probably will issue a secured, first-lien term loan to retire its remaining 2017 and 2018 bonds, the analysts said.

Chesapeake rose 13% to $4.24 at 11:34 a.m. in New York, after earlier jumping 15%. The stock was the biggest intraday gainer in the S&P 500. The advance trimmed Chesapeake’s year-to-date slide to about 6 percent. Last year, shares tumbled 77% for the worst annual performance since 1998.

Chesapeake’s $1.1 billion of 5.75 percent notes maturing in March 2023 jumped 3.25 cents to 36.25 cents on the dollar, according to Trace, the bond-price reporting system of the Financial Industry Regulatory Authority.

Chesapeake’s main focus is 2017 and 2018 “maturity management,” Lawler said in a presentation to analysts last month. The company lost about $40 million a day in 2015 and is expected to end this year in the red as well, based on the average estimate of 14 analysts in a Bloomberg survey.

In addition to most of its gas and oil reserves, Chesapeake pledged as collateral all hedge contracts, property, deposit accounts and securities, subject to certain undisclosed carve-outs, according to the regulatory filing.

The amendment includes a collateral value coverage test, which Chesapeake said may limit its ability to tap the credit line. The revision also provides temporary covenant relief, with a key measure of indebtedness suspended until September 2017. During the grace period, Chesapeake promised to maintain minimum liquidity of $500 million. Chesapeake also maintains the right to incur as much as $2.5 billion of first lien indebtedness.